A question is posted which belongs on another site and ends up already having been asked there. I can't find an example right now, but it's bound to happen soon if it hasn't already.

The same question is posted in two places at the same time. Take this SO question for example, which is a duplicate of this SF question, posted within a half hour of each other by the same user.

Possible actions:

Move it to the proper site and close it once it gets there as a duplicate.

Provide a way to close it right away as a cross-site duplicate, without moving it first.

Flag it and let a moderator merge them.

Close it as "no longer relevant" or something else.

Additionally, flavor 2 is a bit of a special case; perhaps the question really spans both sites in terms of content and intended audience. Should multiple-postings in this case be allowed? If so, should they somehow be linked to each other? If not, how do we avoid a migration war?

As a user, I can't report a duplicate because the answer is on a different site. I can only flag it as a duplicate if it already exists in the same community. There's a lack of proper training or understanding of new users. S/he just want an answer.. doesn't care how the communities should be organized.
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sunk818Sep 26 '14 at 21:28

4 Answers
4

If it is clearly a question that does belong on another site, migrate it and then treat it as duplicate.

If it is a borderline question, let it live in both cultures, as the answeres will be different, programmers answering for programmers, and admins answering for admins.

Yes, it is important to keep the sites focused, but frankly, I am a programmer and will ask questions in SO mainly. So if I have a borderline question I will ask it in SO, not researching SF or SU upfront.

Linking the questions in a comment or the text will be of help and might point me to some additional answers. But I might not understand them, as the answerer expects too much from me as knowledge of the other community goes.

With the growing number of SEs I guess that the number of questions that are ontopic on more than one SE is growing rapidly (wordpress.SE having a very big overlap with stackoverflow.SE, physics.SE with astronomy.SE, ...). This answer should also provide a recommendation for these (open, close, migrate).
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TrilarionJul 21 '14 at 15:44

You can't assume that all users will be on all sites. Each site has to stand on its own merits and you have to treat each site as a separate community.

If a question is inappropriate on one site, users now have alternate places to go with it. It's a nice convenience if moderators choose to transfer it for them. If it turns out to be to be a duplicate, let the other community handle it with the means already in place. If the first moderator happens to spot it as a cross-site duplicate, it can simply be closed and the original poster can decide how to rework the question if they want to try it on another site.

In the edge case where the question is appropriate on more than one site, leave it on both sites and let the users of each community benefit from the information.

There should be a feature for sharing a question between sites for your last edge case. I imagine it would be a product and architectural challenge to implement, and might not be urgent, but eventually.
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ripper234Feb 23 '12 at 9:24

2

With the growing number of stackexchanges isn't there the risk that more and more overlap (Mathematics, Computer Vision, Computer Science, MathOverflow, ...) will lead to more and more x-site-duplicates that are ontopic on several SEs. Should we really leave them everywhere?
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TrilarionJul 21 '14 at 15:46

migrated it to Stack Overflow to have it closed there (Shog9 will kill me)

ignore the question and keep it on Super User as an additional source of information

However the Stack Overflow version has several answers and an accepted answer, so I don't expect Super User to really add new value. Anyone interested can find his answer by following the link, which is consistent with how it works all over the site.

But also looking forward at potential new members of the SO-family it will be increasingly more useful for users to point to OTHER SO-sites for their answers in a consistent matter. Especially for topics like web-app or iPhone/iPad questions on Super User having the ability to link to a future site would help a lot!

i'd've migrated it, with a comment linking to the existing dupe, and flagged the newly-migrated question for a SO mod to close it as duplicate. not sure i'm crazy about the duplicate link you added -- under the principle of least surprise, it should at least show some indication that the link leads offsite. (i've edited to fix, but this isn't normally done so we may be establishing a precedent here...)
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quack quixoteApr 7 '10 at 22:06

@quack hmm, I am not sure these are really duplicates, in fact I feel strongly that they aren't. Are they related? Sure. But duplicate, no. Anyway, I reopened and edited out the dupe link in the body -- it's appropriate to leave a related link in the comments though.
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Jeff Atwood♦Apr 8 '10 at 3:14

@Jeff: ACK!... that'll teach me to leap before looking. you're right, those are similar/related but not duplicates. i must admit i don't think i followed the SO link earlier, just assumed Ivo was linking to a crosspost -- ie a literal, exact duplicate.
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quack quixoteApr 8 '10 at 4:44

If we can't do cross site duplicates, a rep factory is created, and double work is done for nothing. Many border-line questions have precise and identical answers independent of where they were asked.
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Ciro Santilli 六四事件 法轮功Dec 17 '13 at 16:41

I don't think it's any different to duplicates on one site. First step is migration, and then let that community discover/handle the duplicate. When we come across these on SO, we vote to close one based upon its activity, date, structure, etc. I think the same course of actions would be sufficient for cross-site dupes.